Preparation And Cure Kinetic Study Of The Reactive Imide/Multifunctional Epoxide

With the development of aerospace and other fields, the demand for high-performance materials is also increasingly urgent. Epoxy resin with good mechanical properties, excellent insulation properties, high adhesion, low shrinkage, good stability and so on is widely used. However, poor resistance to impact, poor toughness, low heat resistance and other properties of epoxy resin also greatly limit its applications. Therefore, how to improve the heat resistance of epoxy resin is neccesary. In this thesis the polyimide with hydroxyl groups which has excellent properties such as good heat resistance was designed and prepared, then it was used to modify epoxy resin to get the adhesive which will have good mechanical and heat properties.The diamines and polyimides with reactive hydroxyl groups were synthsized firstly in this thesis. The reactiveties of the prepared polyimides were improved while the heat resistance and mechanical properties of the polyimides were kept. The curing kinetics analysis of N,N,N',N'-tetraglycidyl-4,4'-diamino phenyl methane (TGDDM) with aromatic diamines and polyimide with active hydroxyl groups was studied with DSC methods. The results showed that the reactivities of the curing regents with reactive hydroxyl groups were improved. Meanwhile the data will provide a theoretical basis for the curing of the epoxy resin. The epoxy/polyimide adhesive was got through cross-linking reaction. In this thesis, the diamine monomers of the polyimide containing hydroxyl groups were designed and synthesized. Then the polyimides containing hydroxyl groups were prepared by two-step method and the properties of the polyimides were studied. The curing kinetics of TGDDM with aromatic diamines and polyimide powder containing hydroxyl as curing agent were investigated. Finally, polyimide/epoxy resin adhesive was prepared and its performance was studied.This thesis mainly contained six parts:1.3,3'-diamino-4,4'-dihydroxybiphenyl(DADHBP),2,2-Bis(3-amino-4-hydroxy phenyl)propane(BAHPPP),2,2-Bis(3-amino-4-hydroxyphenyl)1,1,1,3,3,3-hexa fluoropropane (BAHPFP) were synthesized through two steps. Then three compounds were characterized by FI-IR and DSC.2. A series of polyimides were prepared by 3,3'-diamino-4,4'-dihydroxybiphenyl (DADHBP),2,2-bis-[4-(4-aminophenoxy)phenyl]propane(BAPOPP) and,3,3',4,4'-tetracarboxylicdiphenylether dianhydride(ODPA) with different ratios in the presence of dimethylacetamide (DMAC) as solvent.2,2-Bis(3-amino-4-hydroxy phenyl)propane(BAHPPP) and 2,2-Bis(3-amino-4-hydroxyphenyl) 1,1,1,3,3,3-hexafluoropropane (BAHPFP) were reacted with ODPA to get the polyimides. The tests of DSC, TGA, FTIR, UV-visible transmittance, contacting angle, water absorption and mechanical performance were performed on the series of polyimide films.3. The polyimide powder containing hydroxyl groups was preparared by copolymerizing of DADHBP, BAPOPP, ODPA, and 3,3',4,4'-Benzophenonetetra carboxylicdianhydride (BTDA). Then the polyimide powder was characterized by FTIR, and the thermal properties were studied by DSC and TGA.4. The exothermic curves of DADHBP and BAHPFP with TGDDM were determined respectively by differential scanning calorimetry (DSC) measurements at different heating rates. The curing kinetics of the two non-isothermal curing processes were studied by Kissinger and Ozawa methods to calculate the average activation energyis were 65.7kJ/mol and 120.2kJ/mol (TGDDM/BAHPFP),109.18kJ/mol and 143.1kJ/mol(TGDDM/DADHBP). The reaction orders were 0.91 and 0.93 (TGDDM/BAHPFP),0.93and 0.94(TGDDM/DADHBP) calculated through Crane equation suggested that the curing processes were complicated. Finally the frequency factor (A) and the reaction rate constant (kp) were calculated by Kissinger and Arrhenius equations.5. The DSC exothermic curves of the adhesive systems of PI/TGDDM and the PI/DDS/TGDDM (containing curing reagent) were determined. Then the kinetics of the above systems were studied by Kissinger and Ozawa equations to get the average activation energies of 131.13kJ/mol(PI/TGDDM) and 108.65kJ/mol(PI/ DDS/TGDDM), while the reaction order were calculated by Crane equation of 0.93(PI/TGDDM) and 0.92(PI/DDS/TGDDM. Finally the frequency factor (A) and the reaction rate constant (kp) were calculated by the Kissinger equation. The results suggested that the two curing reactions were complicated.6. The PI/TGDDM adhesive was perepared firstly. Then the PI/TGDDM was cured. The results showed that the water absorption of PI/TGDDM adhesive was 0.49%. The activation energy of PI/TGDDM adhesive was 64.5kJ/mol.